TYPHOID

Last updated: 06 September 2004

1. Reason for surveillance

• To identify the source of the infection and to prevent further cases

• To monitor the epidemiology to inform the development of better prevention strategies.

2. Case definition

A confirmed case requires laboratory definitive evidence only.

Laboratory definitive evidence
Isolation or detection of Salmonella Typhi.

Epidemiological evidence
Not applicable.

Factors to be considered in case identification
Laboratory diagnosis of typhoid involves the isolation of S. Typhi in blood, urine, faeces or other clinical specimens. Serological testing is unreliable, but occasionally may be useful in cases in which cultures are negative (because of delays in diagnosis or treatment): Salmonella O-agglutination (Widal) titres of ≥160 are strongly associated with infection with S. Typhi. Because antibiotic resistance is common overseas, sensitivity testing is recommended.

3. Notification criteria and procedure

Typhoid is to be notified by:

• Hospital CEOs on clinical diagnosis (ideal reporting by telephone on same day of diagnosis).

Salmonella infection is to be notified by:

• Laboratories on isolation of S. Typhi (ideal reporting by phone or routine mail).

Only confirmed cases should be entered onto NDD. Note: Salmonella Paratyphi infections should be entered on NDD under Salmonellosis.

4. The disease

Infectious agent
Typhoid is caused by the bacteria Salmonella Typhi.

Mode of transmission
Typhoid is transmitted by the faecal-oral route, primarily by ingesting food or water contaminated by faeces or urine.

Timeline
The typical incubation period can vary from 3 days to 1 month, usually 8 to 14 days. Typhoid is infectious while stools are positive, which can vary from weeks to months. Some cases (<5%) become chronic carriers.

Clinical presentation
Typhoid is often characterised by a subtle onset of fever, headache, malaise, bradycardia, splenomegaly, constipation or diarrhoea and non-productive cough. Rose spots on the trunk may occur. Asymptomatic and atypical cases can occur, especially among children.

5. Managing single notifications

Response time
Investigation
On same day of notification of confirmed case begin follow-up investigation.

Data entry
Within 1 working day of notification enter confirmed cases on NDD.

Within 1 working day of notification of the serogroup of the organism, update NDD.

Response procedure
The response to a notification will normally be carried out in collaboration with the case's health carers. But regardless of who does the follow-up, PHU staff should ensure that action has been taken to:

• Confirm the onset date and symptoms of the illness

• Confirm results of relevant pathology tests, or recommend the tests be done

• Find out if the case or relevant care-giver has been told what the diagnosis is before beginning the interview

• Seek the doctor's permission to contact the case or relevant care-giver

• Review case and contact management

• Establish whether the case works in a sensitive occupation, including food handling, or caring for patients, children or the elderly

• Identify the likely source.

Case management
Investigation and treatment
Treatment is the responsibility of the caring doctor. Refer to Therapeutic Guidelines: Antibiotic for specific therapy. Antibiotic resistance testing is important in guiding treatment.

If the case has recently travelled overseas, determine what countries were visited and whether typhoid vaccination was given, including dates.

Education
The case or relevant care-giver should be informed about the nature of the infection and the mode of transmission. Emphasise the importance of hygienic practices, particularly hand washing before eating and preparing food and after going to the toilet.

Isolation and restriction
The case should not be released from medical supervision until 3 consecutive stool cultures are negative AND all of the following apply:

• Specimens were collected ≥1 month after onset

• Specimens were taken ≥48 hours after the cessation of antibiotic therapy

• Specimens were taken ≥24 hours apart.

Urine samples must be collected in addition to stool samples if the case originally had and of the following:

• A positive urine culture

• A history of urinary tract infection

• A history of schistosomiasis.

If any of these cultures are positive, collection should be repeated at monthly intervals until ≥3 consecutive cultures are negative.

If the case is a food handler or provides direct care to patients, children or the elderly, then they should be excluded from those activities until the above criteria are met. A public health order may be taken out against a case who refuses to comply, since such action is likely to endanger the health of the public.

Environmental evaluation
Where a food source is suspected on epidemiological grounds, contact NSW Food Authority Foodborne Outbreak Coordinator to arrange for an environmental evaluation, including sampling residual material (eg, food), assessment of factors contributing to food contamination and reduction of risk.

Contact management
Identification of contacts
Persons at risk of infection are those who have been exposed to a source of infection in a way likely to facilitate transmission of the disease. They include household members, carers of the case and people who may have eaten the implicated food or drink.

Investigation and Treatment
For household contacts, or contacts who were exposed to the same source (for example while travelling overseas) recommend 2 stool samples be taken ≥24 hours apart. Routine immunisation with typhoid vaccine is of limited value for family, household and patient contacts who have been exposed to active cases. It should be considered for those who may be exposed to carriers. Antibiotic prophylaxis is not recommended.

Isolation and restriction
Household contacts who are employed in sensitive occupations, such as food handling, caring for children, the elderly or patients should be excluded from work until 2 negative stool specimens taken ≥24 hours apart are obtained. The reason for this is that chronic carriers may continue to excrete organisms while being treated or waiting for screening.

Other contacts are not restricted, and require education only.

Education
Close contacts and others at risk should be encouraged to seek medical attention early if symptoms develop, and stool samples should be taken. Emphasis should be given to good hygiene practices.